In vivo calibration of the T2* cardiovascular magnetic resonance method at 1.5 T for estimation of cardiac iron in a minipig model of transfusional iron overload

Quantification of Cardiac Iron Overload at 3 T MRI in a Rabbit Model Utilizing ME-GRE T2* Sequence

BACKGROUND

Myocardial iron overload can lead to myocardial dysfunction, muscle cell injury, and end-stage heart failure. The enhanced signal-to-noise ratio and technical advancements have made 3 T magnetic resonance imaging (MRI) more accessible in clinical settings. However, 3 T assessments for early diagnosis of myocardial iron overload are scarce.

PURPOSE

To evaluate the feasibility of myocardial iron quantification using 3 T MRI in a rabbit model of iron overload.

STUDY TYPE

Animal model.

ANIMAL MODEL

Overall, 40 male New Zealand white rabbits were categorized into control (N = 8; no treatment) and experimental (N = 32; weekly 200 mg/kg iron dextran injections) groups.

SEQUENCE

3 T MRI with multi-echo gradient echo (ME-GRE) T2* sequence.

ASSESSMENT

Each week, two experimental rabbits were randomly selected for blood collection to determine serum iron (SI) levels; their tissue was harvested to assess myocardial and hepatic iron deposition.

STATISTICAL TESTS

Spearman's rank correlation tests were used to evaluate the correlations among R2*, cardiac iron concentration (CIC), liver iron concentration (LIC), total amount of iron injected, and SI levels. P ≤ 0.05 was considered statistically significant.

RESULTS

The myocardial T2* value in the experimental group was significantly lower than that of the control group. An excellent correlation was observed between R2* values and CIC (r = 0.854). CIC moderately correlated with LIC (r = 0.712) and the total amount of iron injected (r = 0.698). A strong correlation was observed between the total amount of iron injected and LIC (r = 0.866). SI levels poorly correlated with the total amount of iron injected (r = 0.205, P = 0.277) and LIC (r = 0.170, P = 0.370) but fairly correlated with CIC (r = 0.415, P = 0.022).

DATA CONCLUSION

A 3 T MRI with an ME-GRE sequence may serve as a noninvasive method for evaluating cardiac iron content.

EVIDENCE LEVEL

N/A TECHNICAL EFFICACY: Stage 1.

Evaluation of iron deposition in diabetic kidney disease using the kidney-to-muscle signal intensity ratio on routine MRI T2WI sequences

OBJECTIVE

The T2* technique in Blood Oxygen Level Dependent Magnetic Resonance Imaging (BOLD-MRI) has been established as a non-invasive standard for quantifying tissue iron levels. This study aims to assess the feasibility of obtaining quantitative iron-sensitive information from conventional MRI T2-weighted imaging (T2WI) sequences, typically used for anatomical rather than quantitative assessments, and to explore its potential as a routine monitoring tool for renal iron levels in diabetic kidney disease (DKD).

METHODS

A total of 142 patient imaging data from renal MRI scans were retrospectively analyzed. We measured the kidney and psoas major muscle signal intensity on T2WI sequences and calculated the kidney-to-muscle signal intensity ratio (K/M-SIR) to determine differences across patient groups. Relevant laboratory indices were collected to analyze the correlation between K/M-SIR and laboratory markers.

RESULTS

We included 42 clinically confirmed DKD patients, 47 patients with diabetes but no DKD, and 53 healthy subjects. The K/M-SIR was 2.66 ± 0.49 in DKD patients, 2.94 ± 0.51 in diabetic patients without DKD, and 2.95 ± 0.55 in healthy subjects. There were statistically significant differences in K/M-SIR between DKD patients and healthy subjects (p = 0.008) and between DKD patients and diabetic patients without DKD (p = 0.009). K/M-SIR values were negatively correlated with laboratory indices such as glycated hemoglobin (HbA1c), microalbuminuria (MAU), albumin-to-creatinine ratio (ACR), and 24-hour urinary protein (24 h UP).

CONCLUSION

The kidney-to-muscle signal intensity ratio (K/M-SIR) derived from routine MRI T2WI sequences is valuable for diagnosing DKD and may serve as a reliable non-invasive marker for assessing renal iron deposition in DKD, potentially aiding in the diagnosis and monitoring of DKD severity.

Extracts of Portulaca oleracea promote wound healing by enhancing angiology regeneration and inhibiting iron accumulation in mice

Objective

To investigate the role of Portulaca oleracea (POL) in promoting revascularization and re-epithelization as well as inhibiting iron aggregation and inflammation of deep tissue pressure injury (DTPI).

Methods

The hydroalcoholic extract of POL (P) and aqueous phase fraction of POL (PD) were prepared based on maceration and liquid–liquid extraction. The number of new blood vessels and VEGF-A expression level were assessed using H&E stain and Western blot on injured muscle to examine the role of POL different extracts in vascularization. The iron distribution and total elemental iron of injured muscle were detected using laser ablation inductively coupled plasma mass spectrometry (ICP-MS) and Perls’ staining to determine whether POL extracts can inhibit the iron accumulation. Besides, the ability of POL extracts to promote wound healing by combining re-epithelization time, inflammation degree and collagen deposition area were comprehensively evaluated.

Results

In vitro, we observed a significant increase in HUVEC cell viability, migration rate and the number of the tube after P and PD treatment (P < 0.05). In vivo, administration of P and PD impacted vascularization and iron accumulation on injured tissue, evident from more new blood vessels, higher expression of VEGF-A and decreased muscle iron concentration of treatment groups compared with no-treatment groups (P < 0.05). Besides, shorter re-epithelization time, reduced inflammatory infiltration and distinct collagen deposition were associated with administration of P and PD (P < 0.05).

Conclusion

POL extract administration groups have high-quality wound healing, which is associated with increased new blood vessels, collagen deposition and re-epithelization, along with decreased iron accumulation and inflammatory infiltration. Our results suggest that that POL extract is beneficial to repair injured muscle after ischemia–reperfusion, highlighting the potential of POL in the DTPI treatment.